Electrochemical batteries have a very wide range of applications. Such batteries have limited life spans. Over time and with use the condition of a battery is degraded. Eventually the battery is unable to meet requirements. For example, the battery may become unable to hold a charge adequately or at all or it may become unable to supply a desired current. The condition of any particular battery (sometimes called the “state of health” or “SoH”) is a function of the design of the battery, variables relating to the manufacture of the battery, the history of the temperature and other environmental conditions in which the battery has been stored, the number of charge-discharge cycles that the battery has experienced, and the nature of the charge-discharge cycles that the battery has experienced. Because the condition of a battery depends upon so many factors, it is not generally possible to predict reliably when a particular battery will cease to meet applicable specifications.
Where batteries power critical equipment, one can replace the batteries periodically whether or not they appear to need replacing. However, in a group of seemingly identical batteries there can be a broad spread in the time taken for the batteries to fail. This strategy is expensive because it mandates replacing most batteries when a significant portion of their useful life remains.
Another strategy is to monitor the condition of batteries by testing the batteries. Appropriate tests may be able to detect that the condition of a particular battery is becoming worse so that the battery can be replaced before it fails. Some such tests are undesirably time consuming and may require that the battery be in a particular state of charge for the tests to be conducted.
Existing methods for rapid testing of batteries do not work well for batteries of all chemistries. For example, using current tests it can be difficult to obtain rapid accurate measurements of the condition of lithium batteries, especially lithium batteries having cathodes that incorporate manganese.
There is a need for methods and apparatus that can be used to evaluate the condition of electrochemical batteries. There is a particular need for such methods and apparatus that can test batteries rapidly.
The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.